1. Field of the Invention
The present invention relates to a sanding machine for polishing the surface of a metal or wood workpiece and more particularly, to a disc sander, which allows biasing of the sanding mechanism to adjust the angle between the sanding mechanism and the operation platform.
2. Description of the Related Art
A disc sander is adapted for polishing the surface of a metal or wood workpiece. A conventional disc sander generally comprises a housing, a motor mounted in the housing, an operation platform mounted on the housing and adapted for holding a workpiece for sanding, and a sanding wheel rotatable by the motor to sand the workpiece at the operation platform.
Before sanding the workpiece, the angle between the operation platform and the sanding wheel must be adjusted subject to the angle of the surface of the workpiece to be polished so that the surface of the workpiece can be kept in positive contact with the sanding wheel for sanding. Therefore, a conventional disc sander includes an angle adjustment unit for allowing adjustment of the tilting angle of the operation platform relative to the sanding wheel. When sanding the workpiece, the operator must hold the workpiece and push the workpiece into contact with the sanding surface of the sanding wheel. However, because the operation platform is kept in a tilted position, the operator must apply much force to the workpiece against the sanding surface of the sanding wheel, avoiding sliding of the workpiece on the operation platform. When sanding a big size workpiece, it is difficult to hold the heavy workpiece on the tilted operation platform against the sanding surface of the sanding wheel. If the workpiece slides accidentally during sanding, the sanding quality will be affected.